Refractive index via permittivity and permeability
==================================================

Refractive index can be calculated from the relative permittivity and permeability
of the medium.

**Links:**

#. `Wikipedia <https://en.wikipedia.org/wiki/Refractive_index#Relative_permittivity_and_permeability>`__.

..
    TODO move to `electrodynamics` or `optics`?

.. py:currentmodule:: symplyphysics.laws.waves.refractive_index_via_permittivity_and_permeability

.. py:data:: refractive_index

    :attr:`~symplyphysics.symbols.optics.relative_refractive_index` of the medium.

Symbol:
    :code:`n`

Latex:
    :math:`n`

Dimension:
    :code:`dimensionless`


.. py:data:: relative_permittivity

    :attr:`~symplyphysics.symbols.electrodynamics.relative_permittivity` of the medium.

Symbol:
    :code:`epsilon_r`

Latex:
    :math:`\varepsilon_\text{r}`

Dimension:
    :code:`dimensionless`


.. py:data:: relative_permeability

    :attr:`~symplyphysics.symbols.electrodynamics.relative_permeability` of the medium.

Symbol:
    :code:`mu_r`

Latex:
    :math:`\mu_\text{r}`

Dimension:
    :code:`dimensionless`


.. py:data:: law

    :code:`n = sqrt(epsilon_r * mu_r)`


    Latex:
        .. math::
            n = \sqrt{\varepsilon_\text{r} \mu_\text{r}}